Electric cable.



170. 816,428. PATENTED MAR. 27, 1906. H. W. BUCK.

ELECTRIC CABLE.

APPLIGATION FILED JULY 27,1904.

ITIJESSESI HawoldV/BLJcK.

Q v b amfifl to a subwa v,

UNITED STATES PATENT OFFICE.

x 'lIAROLl.) \V. BUCK, ()I NIAGARA FALLS, .NlflV YORK, ASSIHNUR A(.ORPORAIION OF ERAL ELEC'IRH COMPA NY,

T (H lf- NEW YORK.

ELECTRIC CABLE.

Specification of Letters Patent.

Patented March 27, 1906.

A iicaaoifiiia July 27. 1904. Serial No. 218,407.

To (LZZ whom it may concern: Be it known that l, HAROLD W. BUCK, acitizen of the United States, residii'ig at Niagara Falls, in the countyof Niagara and State i of New York, have invented certain new and usefulimprovements in Electric (ables, of

which the following is a specification.

Where a large number of cables are to be located in close proximity toeach other, as in it is necessary that the cables when installed bethoroughly fireproof. The object of my invention is to provide such afireproof installation. It has been proposed heretofore to render ielectric cables fireproof by applying to the cable during the process ofmanufacture it braid which has been previously impregnated with somefireproof liquid. This method of protection, however, has. provedunsatisfaczo tory, because the subsequent coiling and uncoiling of thecompleted cables at the factor v and during the installation cracks thetireproof braid, which is naturally hard and brittlc, and leaves it fullof minute cracks and pores. Under such circumstances in case of aneighboring short circuit or excessive heating in. the conductor of thecable therubber coinpound of the insulation gives off a conibustiblegaswhich comes out through" these cracks'and burns in the form of numerouslittlc gas jets,-Which is practically the equivalent of the rubberburning directly. It has also been proposed to provide the cable, afterithas been installed, with a wrapping of untreated asbestos,'but this isusually no better even where the asbestos is held by a steel binder, forthe reason that the heating of the cable-causes the binder fU llKll anduncoil and allow theasbostos wrapping to fall off, orflif the bindcrdoes not fall off. the rubber i insulation inside of the wrapping meltscomes out through the pores of the asbestos, which acts as a.vicl\'-,,and s o n-*-the.cable is dcst ro vcd. Another objection to theuscof untreated asbestos as a wrapping is that it is a good lilsft-{lat-or 'of heat, and conscipi'cnt l the heat of the eable-eonductor isretained within the wrapping, which thereby direct fva sists inincreasin gthe temperature of the cable. Furthermore,theuseofsteeltapeorwireto hold theasbestos wrappingi i position is ver expensive.Ilho object of the present invention is ;to install an electric cablewhich shall be free from any of the above defects.

i i i i left filled,

In carrying out my invention the cables are placed in their finalposition and then covered with a iii'cproof fibrous material which haspreviously been impregnated with some fireproof self-hardening liquid.Specifically, I employ a strip of asbestos and soak the same in asolution of silicate of soda and then while still wet wrap itabout thecable in place. The silicate of soda is then allowed to harden and allthe pores of the asbestos are so that in case the cable becomes undulyheated the rubber insulation cannot work out through the asbestos andtake fire. Furthermore, the asbestos when so treated becomes a very goodconductor of heat, and thus assists in maintaining the cable at a lowtemperature.

in the accompanying drawings, Figure 1 is an elevation of a cabletreated in accordance with my invention and showing a single strip ofthe fireproof wrapping. Fig. 2 is a similar view showing a wrappincomposed of two F overlapping strips, and Fig. 3 is a cross-section ofasubwav, showing the cable installed. in said dra\\'ings, 1U designatesthe cable, which is provided with the usual covering 1], of rubber orother insulation, upon the outer surface of which is wound the wrapping12. According to li] invention the cable is placed in its final position-as. for example; upon the brackets 13 in the subway H. .\s previouslindicated, when thus positioned a strip of asbestos or equivalentfireproof material is soaked in a silicioiis solution. such assilicatc-of-soda solution, and then when thoroughly impregnated it iswrapped about the cable. It isobvious that this wrapping ina v be done.in different wavsrand for illustration [have shown in Fig. I theimpregnated asbestos strip 1;, spirally wound about the cable. in Fig. 2the singlcstrip is replaced by two overlapping strips 1;? and 12". whichare also spirallywound. l l'tlfll the above it will be apparent that myinvention possesses man advantages over installations of the prior art,

and that while thc covering is hard and brittle it is neverthelesswithout cracks or pores, since it is not moved after it has hardenedupon the cable, but remains solid and honiogcncous. I

lt will be apparent to those skilled in the art that the asbestos inirvbe replaced by other fireproof material and that other sclf hardeningsolutions might bc employed in stead of a silicate-ot-soda solution. I.therefore do not wish my invention to be unduly limited, but aim tocover by the terms of the appended claims all equivalents.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is

l. The method of fireproofing electric ca bles which consists in placingthe cables in 3. The method of fireproofing electric cables whichconsists in placing the cables in their final position, imn'egnatingasbestos with a silicate-of-soda sofution, and wrapping said impregnatedasbestos while wet about the cables so as to completely envelop them.

4. The method of fireproofing electric cables which consists in placingthe cables in their final position, impregnating a strip of asbestoswith a silicious solution, and wra ping the impregnated strip while wetspiral y about the cables so as to completely incase them.

In witness whereof I have hereunto set my hand this 22d day of July,1904.

HAROLD W. BUCK.

Witnesses:

G. E. BROWN, 1. M. INNES.

